Context: For athletes in disciplines with weight categories, it is important to assess body composition and weight fluctuations.Objective: To evaluate the accuracy of measuring body fat percentage with a portable ultrasound device possessing high accuracy and reliability versus fan-beam, dual-energy X-ray absorptiometry (DEXA).Design: Cross-validation study. Setting: Research laboratory. Patients or Other Participants: A total of 93 athletes (24 women, 69 men), aged 23.5 6 3.7 years, with body mass index 5 24.0 6 4.2 and body fat percentage via DEXA 5 9.41 6 8.1 participated. All participants were elite athletes selected from the Institut National des Sports et de l'Education Physique. These participants practiced a variety of weight-category sports.Main Outcome Measure(s): We measured body fat and body fat percentage using an ultrasound technique associated with anthropometric values and the DEXA reference technique.Cross-validation between the ultrasound technique and DEXA was then performed.Results: Ultrasound estimates of body fat percentage were correlated closely with those of DEXA in both females (r 5 0.97, standard error of the estimate 5 1.79) and males (r 5 0.98, standard error of the estimate 5 0.96). The ultrasound technique in both sexes had a low total error (0.93). The 95% limit of agreement was 20.06 6 1.2 for all athletes and did not show an overprediction or underprediction bias. We developed a new model to produce body fat estimates with ultrasound and anthropometric dimensions.Conclusions: I n sport disciplines with weight categories, assessing individual weight fluctuations and their consequences on body composition is important to optimize the performances of athletes during competitions. 1-3 Just before a competition, some athletes need to lose a large quantity of body weight in a short period of time. This weight loss is difficult for many athletes because it often results in poorer performances. 4,5 It is, therefore, necessary to determine each athlete's ideal weight category. For that purpose, knowledge of body composition in relation to total body fat (BF) and fatfree mass (FFM) is required. Optimizing these components is essential for improving physical training for each athlete.To evaluate BF percentage (BF%), a noninvasive portable ultrasound device that measures the thickness of subcutaneous fat and has been validated on sedentary participants can be used. Pineau et al 6 cross-validated the portable ultrasound technique (UT), air-displacement plethysmography, and bioelectric impedance (BIA) with fan-beam, dualenergy X-ray absorptiometry (DEXA) in 89 healthy volunteers. Body fat percentage estimates by UT were more accurate than those obtained with air-displacement plethysmography or BIA, regardless of sex.A cross-validation study between UT and the DEXA reference was carried out and the results compared on 93 athletes. The portable UT measures the thickness of subcutaneous fat. These measurements were taken at specific points on all participants for the estimation of BF, BF%, and F...

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Aims: To evaluate the accuracy of body fat percentage (BF%) estimates from a portable, non-traumatizing ultrasound device with high accuracy and reliability compared to dual-energy X-ray absorptiometry (DEXA), the reference technique. Design: Cross-validation between ultrasound technique (UT), DEXA, air displacement plethysmography (ADP) and bioelectrical impedance (BIA) was developed in the study. Subjects: A total of 89 healthy subjects (41 women, 48 men), aged 48.4 ± 17.7 (mean ± SD), with Body mass index (28.5 ± 7.7 kg/m²) and body fat DEXA (29.6 ± 10.8 kg) participated. Methods: BF% was measured using an UT associated with anthropometric parameters and simultaneously, with the DEXA reference technique, BIA and ADP. Results: UT estimates of BF% were better correlated with those of DEXA in both males and females (r = 0.98, SEE = 2.0) than with ADP (r = 0.94, SEE = 3.7) or BIA (r = 0.92, SEE = 4.4). The UT in both genders was better (TE = 1.0) than BIA (TE = 2.6) and ADP (TE = 3.0). The 95% limits of agreement were also better for the UT (–2%; 2%) than with BIA (–5.1%; 4.9%) and ADP (–6.3%; 5.3%). Conclusions: The limits of agreement with BIA and ADP are unacceptably high compared to a DEXA measure criterion. The use of a new portable device based on a UT produced a very accurate BF% estimate in relation to the DEXA reference technique.